1. Field of the Invention
The present invention relates to a tube connecting apparatus for melting to cut flexible tubes and for connecting the tubes by mutually contacting the cut end faces.
2. Description of the Related Art
A tube connecting apparatus is used, for instance, for transferring a dialysis solution to an abdominal cavity of a patient who requires Continuous Ambulatory Peritoneal Dialysis (CAPD) by providing connection between a transfer tube connected with the abdominal cavity and a tube connected with a dialysis pack.
An example for connecting operations of a tube connecting apparatus will be briefly explained below. As exemplarily shown in FIG. 18, two tubes 7, 8 are grasped at two portions, that is, between a fixed clamp 311 and a movable clamp 312 of a first tube holder 301 and between a fixed clamp 313 and a movable clamp 314 of a second tube holder 302. The movable clamps 312, 314 are moved into contact with, and away from, the fixed clamps 311, 313. The tubes 7, 8 grasped by the first tube holder 301 and the second tube holder 302 are squeezed flat in cross section, closing the interior of the tubes.
Then, a heated cutting plate (hereinafter referred to as a xe2x80x9cwaferxe2x80x9d) 6 is moved upwards between the first tube holder 301 and the second tube holder 302, thereby melting to vertically cut the tubes 7, 8.
In the first tube holder 301 is provided a pair of semicircular rotor pieces 303, 304 which are brought into contact with each other to form a clamp rotor 305.
After the cutting of the tubes 7, 8, the rotation of the clamp rotor 305 grasping the cut tubes (7a, 8a) of one side of the tubes (7, 8), as shown in FIG. 19, inverts the cut tubes 7a, 8a while allowing their cut end faces to slide along a side surface of the wafer 6.
Upon completion of inversion of the cut tubes 7a, 8a, the wafer 6 is retracted when the cut end faces of mutually different tubes (7a and 8b, 8a and 7b) are positioned coaxially, facing each other, and the cut end faces of the different tubes are pressed to each other to be welded. Thus, two tubes 9, 10 are formed as illustrated in FIG. 20.
The above described tube connecting apparatus is arranged such that inversion of the cut tubes is performed by the clamp rotor 305 comprising the pair of rotor pieces 303, 304. FIG. 21 is a sectional view of the clamp rotor 305 mounted in the first tube holder 301.
The clamp rotor 305 includes of the pair of semicircular rotor pieces 303, 304 with teeth formed on the periphery thereof, and is so constituted as to make one gear when the rotor pieces 303,304 come into contact with each other. At a center of the clamp rotor 305, that is, at the center of the contact surfaces of the rotor pieces 303, 304, U-shaped grooves 331, 332 are formed deep enough to allow the insertion of one tube, and closing portions 333, 334 are provided forming shallow grooves to squeeze and grasp the tubes.
The rotor pieces 303, 304 are respectively mounted in rotor mounting portions 323, 324 formed in blocks 321, 322 constituting the fixed clamp 311 and the movable clamp 312.
On the other hand, a drive gear 306 which is in mesh with the rotor piece 303(304) is rotatably mounted in a gear mounting portion 325 formed continuously to the rotor mounting portion 323. The drive gear 306 is further connected to a motor shaft of a driving motor (not illustrated).
When the tubes 7, 8 are grasped and then cut as shown in FIG. 18, the unillustrated driving motor is driven at a specified timing such that rotation is transmitted to the driving gear 306. In this manner, the clamp rotor 305 is rotated within the first tube holder 301 and the rotor pieces 303, 304 are turned to change the placement of cut tubes 7a, 8a. 
However, the conventional tube connecting apparatus mentioned above has the following disadvantages.
(1) The first and second holders 301, 302 need to be moved closer to each other for securing operations of pressing the cut end faces of the tubes to each other after retracting the wafer 6. Therefore, for clamping the tubes 7, 8 by the first tube holder 301 and the second tube holder 302, the movable clamp 312 is fixed to the fixed clamp 311 and, separately therefrom, the movable clamp 314 is fixed to the fixed clamp 313. In this way, in order to fix the movable clamps 312, 314 to the fixed clamps 311, 313, similar works need to be repeated, of manually or automatically, thereby causing useless redundancy in view of operation as well as structural arrangement.
(2) The conventional tube connecting apparatus employing the clamp rotor 305 is arranged such that the rotor pieces 303, 304 are exposed to the exterior when the blocks 321, 322 are separated. In case the user presses the rotor pieces 303, 304, therefore, the rotor pieces 303, 304 will be displaced from each position after tube connection where the tubes are held symmetrically with respect to each other.
Thus, in case the rotor pieces 303, 304 should be brought into contact with each other while still displaced, either one will be pushed by the other to be slightly rotated. Thus the clamp rotor 305 will be misaligned relative to a reference condition in which the rotor pieces 303, 304 are accurately mounted in symmetric relation to each other in the blocks 321, 322 as shown in FIG. 21. Accordingly, if the apparatus is actuated in this condition with the tubes 7, 8 being not clamped symmetrically, misalignment of the cut end faces of the tubes 7, 8 is caused by inversion of the clamp rotor 305, which may result in connection errors.
(3) While the tubes 7, 8 are clamped by the first and second tube holders 301, 302, if the movable clamps 312, 314 are erroneously separated from the fixed clamps 311, 313 before the tubes 9, 10 are formed, i.e., before the tubes 7, 8 are alternately joined to each other, the tubes 7, 8 will be released from the first and second holders 301, 302. As a result, the alternate joining of the tubes 7, 8 can not be ensured. It is therefore necessary to prevent the fixed clamps 311, 313 from being separated from the movable clamps 312, 314 before completion of alternate connection of the tubes. However, the conventional apparatus is provided with no functions for reliable of such an event prevention.
The present invention has been made in view of the above circumstances and has an object to overcome the above problems and to provide a tube connecting apparatus capable of reliably connecting tubes.
Additional objects and advantages of the invention will be set forth in part in the description which follows and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the purpose of the invention, there is provided a tube connecting apparatus including: a first tube holder provided with a pair of holding members for holding a plurality of flexible tubes; a second tube holder provided with a pair of holding members for holding the plurality of flexible tubes, one or both of the first tube holder and the second tube holder including a pair of rotatable clamping members for holding the tubes, the clamping members including separable pieces disposed in rotational symmetry; cutting and connecting means for heating and melting the plurality of flexible tubes held in the first tube holder and the second tube holder to cut the tubes by a heated cutting plate which is moved between the first tube holder and the second tube holder and to connect the tubes cut by the cutting plate by contacting cut end faces of the cut tubes held in the first tube holder with those of the cut tubes held in the second tube holder, the cut tubes to be connected being parts of originally different tubes; and rotation preventing means for preventing rotation of the clamping members being in predetermined positions in the respective holding members while the pair of clamping members are in a state of not holding the plurality of flexible tubes.
In the above tube connecting apparatus, while the clamping members are not in a clamping position with respect to the tubes, the rotation preventing means functions to prevent the rotation of the clamping members to lock them in position within the respective holding members. Thus, the connection of tubes can be reliably ensured.
In the above tube connecting apparatus, preferably, the rotation preventing means is constructed of an engaging groove formed in the clamping member and a protrusion provided in a resilient member having an urging force toward the clamping member, the protrusion being insertable into the groove of the clamping member by the urging force of the resilient member, and the protrusion is retracted from the groove of the clamping member against the urging force of the resilient member by a pressing member that presses the resilient member away from the clamping member when the pair of clamping members hold the tubes.
In the above tube connecting apparatus, preferably, the resilient member is a flat spring and is integrally formed with the protrusion insertable into the groove of the clamping member.
Preferably, the groove of the clamping member is formed in the clamping member in a correspondent position with the protrusion.
Preferably, the rotation preventing means is constructed of an engaging groove formed in the clamping member, an engaging slider formed with an engaging portion insertable into the groove of the clamping member, and a linkage mechanism for sliding the engaging slider forward and backward in synchronization with the pair of holding members operated to hold and release the tubes.
Preferably, the linkage mechanism of the rotation preventing means includes a lever axially supported so as to be able to oscillate, the lever being oscillated by an external force applied thereto when the pair of holding members hold the tubes, thereby retracting the engaging slider urged to the clamping member against the urging force.
Preferably, the groove of the clamping member is formed in the clamping member in a correspondent position with the engaging portion.
According to another aspect of the invention, there is provided a tube connecting apparatus including: a first tube holder provided with a pair of holding members for holding a plurality of flexible tubes; a second tube holder provided with a pair of holding members for holding the plurality of flexible tubes, one or both of the first tube holder and the second tube holder including a pair of rotatable clamping members for holding the tubes, the clamping members including separable pieces disposed in rotational symmetry; cutting and connecting means for heating and melting the plurality of flexible tubes held in the first tube holder and the second tube holder to cut the tubes by a heated cutting plate which is moved between the first tube holder and the second tube holder and to connect the tubes cut by the cutting plate by contacting cut end faces of the cut tubes held in the first tube holder with those of the cut tubes held in the second tube holder, the cut tubes to be connected being parts of originally different tubes; wherein at least either one of the holding members of at least either one of the first tube holder and the second tube holder is provided with a positioning hole and the other one with a positioning protrusion engageable with the positioning hole, and positioning of the pair of holding members set together is performed by engaging the protrusion with the positioning hole.
In the above tube connecting apparatus, with the positioning hole and the positioning protrusion, the pair of holding members of the first tube holder and/or the second tube holder can be set in position with respect to each other, which makes it possible to reliably grasp the tubes and squeeze them flat. Accordingly, the interiors of the tubes squeezed can be tightly closed to prevent liquid leakage therefrom when the tubes are cut.
According to another aspect of the present invention, there is provided a tube connecting apparatus including: a first tube holder provided with a pair of holding members for holding a plurality of flexible tubes, a second tube holder provided with a pair of holding members for holding the plurality of flexible tubes; cutting and connecting means for heating and melting the plurality of flexible tubes held in the first tube holder and the second tube holder to cut the tubes by a heated cutting plate which is moved between the first tube holder and the second tube holder and to connect the tubes cut by the cutting plate by contacting cut end faces of the cut tubes held in the first tube holder with those of the cut tubes held in the second tube holder, the cut tubes to be connected being parts of originally different tubes; and supporting means provided in at least either one of the first tube holder and the second tube holder for supporting the tubes one over another.
Accordingly, at least one of the first and second tube holders is provided with the supporting means for supporting the tubes therein, so that the tubes can be reliably held one over another in the holding members, preventing connection errors.
In the tube connecting apparatus, preferably, the supporting means is provided with a pair of supporting claws projecting for pinching the tubes therebetween, each of the supporting claws being formed with a protrusion for preventing the tubes from coming off.
According to another aspect of the present invention, there is provided a tube connecting apparatus including: a first tube holder provided with a pair of holding members for holding a plurality of flexible tubes; a second tube holder provided with a pair of holding members for holding the plurality of flexible tubes; cutting and connecting means for heating and melting the plurality of flexible tubes held in the first tube holder and the second tube holder to cut the tubes by a heated cutting plate which is moved between the first tube holder and the second tube holder and to connect the tubes cut by the cutting plate by contacting cut end faces of the cut tubes held in the first tube holder with those of the cut tubes held in the second tube holder, the cut tubes to be connected being parts of originally different tubes; and detecting means for detecting presence or absence of the tubes in at least one of the first tube holder and the second tube holder.
The tube connecting apparatus provided with the detecting means which detects the presence/absence of the tubes can avoid the connection errors caused by clamping errors with respect to the tubes.
In the above tube connecting apparatus, preferably, the detecting means includes a plunger which protrudes in response to urging force of urging members and a sensor for detecting a position of the plunger, and the plunger is retracted by an elastic force of the held tubes against the urging force of the urging members and a position of the retracted plunger is detected by the sensor.
Preferably, the plunger is provided in either or both of the tube holders and a surface from which the plunger projects is flat.
Preferably, the pair of holding members is formed with a groove for holding the tubes, the groove being formed with closing members for flattening and closing the held tubes at one end thereof, the plunger is disposed within the groove, and a closing position at which the closing members close the tubes is closer to the plunger side than a center of the tubes.
According to another aspect of the present invention, there is provided a tube connecting apparatus including: a first tube holder provided with a pair of holding members for holding a plurality of flexible tubes; a second tube holder provided with a pair of holding members for holding the plurality of flexible tubes, one or both of the first tube holder and the second tube holder including a pair of rotatable clamping members for holding the tubes, the clamping members including separable pieces disposed in rotational symmetry; cutting and connecting means for heating and melting the plurality of flexible tubes held in the first tube holder and the second tube holder to cut the tubes by a heated cutting plate which is moved between the first tube holder and the second tube holder and to connect the tubes cut by the cutting plate by contacting cut end faces of the cut tubes held in the first tube holder with those of the cut tubes held in the second tube holder, the cut tubes to be connected being parts of originally different tubes; and supporting means for arranging the tubes one over another in an outside of at least either one of the first tube holder and the second tube holder; wherein the supporting means includes a pair of claws for pinching the tubes therebetween, the claws being urged in directions of moving toward each other by urging members and being movable away from each other in association with rotation of the tubes against the urging force of the urging members while the tubes are rotated as held by the clamping member.
Since the above tube connecting apparatus is provided with the supporting means constructed of a pair of claws for pinching the tubes therebetween with the aid of the urging members which urge the claws in directions of moving toward each other, the claws being movable away from each other against the urging force in correspondence with the rotation of the tubes, the tubes can be reliably held one over another. Specifically, the tubes when disposed one on top of the other can be surely supported in position, while the tubes can be smoothly inverted due to mutual outward sliding of the claws.